Carbon-carbon bond cleavage and rearrangement of benzene by a trinuclear titanium hydride
Carbon-carbon bond cleavage and rearrangement of benzene by a trinuclear titanium hydride
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DOI：
10.1038/nature13624
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发表时间：
2014-08-28
期刊：
影响因子：
64.8
通讯作者：
Hou, Zhaomin
中科院分区：
文献类型：
--
作者：
Hu, Shaowei;Shima, Takanori;Hou, Zhaomin
过渡金属对碳-碳（C-C）键的裂解引起了极大的兴趣，特别是这种转化可以用来从石油和生物质等自然资源中生产燃料和其他工业上重要的化学物质。碳-碳键非常稳定，因此在许多反应条件下不发生反应。在工业石脑油加氢裂化过程中，苯的芳香碳骨架可以通过固体催化剂表面的C-C键裂解和重排转化为甲基环戊烷和无环饱和烃（1-6）。然而，这些化学转化通常需要高温，而且是非选择性的。微生物可以在环境条件下降解芳香族化合物，但其机理细节尚不清楚，也很难模拟(7)。据报道，一些过渡金属配合物在特殊情况下以选择性的方式切割C-C键，例如减轻环应变，形成芳香体系，螯合辅助环金属化和β -碳消除（8-15）。然而，过渡金属配合物对苯的裂解尚未见报道（16-19）。本文报道了三核钛多氢化物配合物对苯的C-C键的裂解和重排。苯环通过多钛位点上芳碳骨架的裂解，依次转化为甲基环戊烯基和2-甲基戊烯基。我们的研究结果表明，多核钛氢化物可以作为芳香分子活化的独特平台，并可能促进设计新的非活性芳烃转化催化剂。
The cleavage of carbon-carbon ( C-C) bonds by transition metals is of great interest, especially as this transformation can be used to produce fuels and other industrially important chemicals from natural resources such as petroleum and biomass. Carbon-carbon bonds are quite stable and are consequently unreactive under many reaction conditions. In the industrial naphtha hydrocracking process, the aromatic carbon skeleton of benzene can be transformed to methylcyclopentane and acyclic saturated hydrocarbons through C-C bond cleavage and rearrangement on the surfaces of solid catalysts(1-6). However, these chemical transformations usually require high temperatures and are fairly non-selective. Microorganisms can degrade aromatic compounds under ambient conditions, but the mechanistic details are not known and are difficult to mimic(7). Several transition metal complexes have been reported to cleave C-C bonds in a selective fashion in special circumstances, such as relief of ring strain, formation of an aromatic system, chelation-assisted cyclometallation and beta-carbon elimination(8-15). However, the cleavage of benzene by a transition metal complex has not been reported(16-19). Here we report the C-C bond cleavage and rearrangement of benzene by a trinuclear titanium poly-hydride complex. The benzene ring is transformed sequentially to a methylcyclopentenyl and a 2-methylpentenyl species through the cleavage of the aromatic carbon skeleton at the multi-titanium sites. Our results suggest that multinuclear titanium hydrides could serve as a unique platform for the activation of aromatic molecules, and may facilitate the design of new catalysts for the transformation of inactive aromatics.